1. Field of the Invention
This invention relates to an image simulation technique for performing processing of mapping a texture to specified faces of a three-dimensional image shown on a display. More particularly, the invention relates to an image simulation technique that allows one to change mapping form of a texture easily and flexibly.
2. Description of the Related Art
Image simulation techniques are known for checking how a three-dimensional image will look by mapping a separate texture to specified faces of the image shown on a display. The inventor has applied an invention according to such image simulation techniques (refer to Patent Document 1, for example).                [Patent Document 1: Japanese Patent Laid-Open No. 2000-222606]        
If the art in Patent Document 1 is used, for example, in changing exterior walls of a building for remodeling, an image of the building is captured and the image of its exterior walls is replaced with an image of a wall material that will be used so that an image showing how the building looks after remodeling is generated. Technically, position information for the building is expressed as virtual three-dimensional coordinates, and an exterior wall is recognized as a plane in the coordinates. Then, with consideration of the orientation and size of the recognized plane, repetition of a wall material image is displayed over the exterior wall so that image simulation is carried out. In the process, wall patterns (referred to as “joint”) may not match at a position where neighboring exterior walls meet because of difference of the drawing start points for the wall material mapped to one exterior wall and another exterior wall that are contiguous to each other or because of calculation error of the number of times with which a wall material is mapped to two exterior walls.
Conventional arts for adjusting such mismatch of a pattern of a texture mapped to planes of a three-dimensional (3D) image include one as follows: a screen is displayed for a user to enter or modify the drawing start points and the number of drawing iterations for a texture, thereby making an adjustment to eliminate such mismatch of patterns. In such a conventional art, when the user wants to check how a 3D image will look by mapping a separate texture to specified faces of the 3D image shown on a display, the user will repeat an operation of inputting the drawing start positions of the texture and the number of drawing iterations using a screen for entering the information and seeing how mismatch of the wall pattern is displayed correspondingly.
The art poses a problem that a significant amount of time and effort is required from a user to adjust mismatch of a texture pattern because the user cannot know what range of values he/she should input intuitively and thus performs this operation by trial and error. In addition, the operation requires an additional time and effort from a user who does not have technical knowledge about spatial coordinates that is necessary for understanding the relation between the drawing start position of a texture or increase/decrease of the number of drawing iterations and a corresponding presentation of the texture.